I had a really bad hatch this week. Out of 16 eggs, only 7 hatched, and one of those hatched late and wasn't able to survive. I'm not sure yet about another.
Half of these eggs were pretty large, and only two of the large eggs hatched.
I went back through my notes, and while I haven't recorded actual egg size I did learn that my Marans and MaransX (extra large eggs) have hatched less than a quarter of the set eggs.
I was doing some research online and found one article from a professional hatchery that talked about this. It said that large eggs hatched at the normal temperatures hatch at lower rates because as the chicks fill the shell they can't shed heat as well. They overheat in the last ten days of incubation and can't make it to hatch.
When they hatch large eggs, it said that in the last ten days they gradually reduce the temperature to 99.1. It was very gradual, which my incubator can't handle, but I was thinking about doing a test.
Extra large eggs only, as defined by "eggs that don't fit in a standard carton," set at 99.5 until day 12, then reduced to 99. I would expect a bit of a late hatch.
I would also check the temperatures of the eggs daily. I suspect that any eggs that are overheating would be pretty obvious.
Half of these eggs were pretty large, and only two of the large eggs hatched.
I went back through my notes, and while I haven't recorded actual egg size I did learn that my Marans and MaransX (extra large eggs) have hatched less than a quarter of the set eggs.
I was doing some research online and found one article from a professional hatchery that talked about this. It said that large eggs hatched at the normal temperatures hatch at lower rates because as the chicks fill the shell they can't shed heat as well. They overheat in the last ten days of incubation and can't make it to hatch.
When they hatch large eggs, it said that in the last ten days they gradually reduce the temperature to 99.1. It was very gradual, which my incubator can't handle, but I was thinking about doing a test.
Extra large eggs only, as defined by "eggs that don't fit in a standard carton," set at 99.5 until day 12, then reduced to 99. I would expect a bit of a late hatch.
I would also check the temperatures of the eggs daily. I suspect that any eggs that are overheating would be pretty obvious.
